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Cognition in radio communication is a valuable means of improving spectrum utilization and can contribute to reducing energy consumption in wireless communication systems. This paper proposes a power control scheme using spectrum hole lifetime to diminish cognitive radio energy consumption. The secondary users' transmission power level will be adapted in different licensed channels subject to the...
A major challenge in the two-tier femtocell networks-comprised of a central macrocell underlaid with femtocells is the efficient use of radio resources. Power optimization technique is one important component of radio resource management, since the deployment of femtocells may cause serious cross-tier interference and consume large amounts of energy. This paper presents an energy-efficient power control...
In this paper we profile a particular tradeoff between power budget and video quality that emerges in the transmission of multimedia packets over a wireless channel. These packets are due to arrive to a receiver at a particular time, so we consider a finite horizon problem over which multimedia data are transmitted. Due to the lossy nature of the wireless channel, however, not every packet can be...
This paper contains two parts. The first part presents a novel framework for the successive convex approximation (SCA) method to solve a general optimization problem, as well as its properties. This framework starts with making change of variables (COV), motivated by the fact that it might be easier to construct convex approximations for the problem after making the COV. Furthermore, a general method...
Power control plays a key role in realizing reliable and spectrum-efficient communications in a cognitive radio network. In this paper we study secure power control schemes for cognitive radios via a robust Markov decision process (MDP) approach. We first use the discrete time Markov chain (DTMC) model to characterize the primary user's (PU) activities as well as the dynamics of the fading channel...
We investigate the problem of distributed scheduling and power control for vertical spectrum sharing in spatial-reuse time division multiple access (STDMA) networks. The objective is to minimize the transmission length (in term of time slots) of secondary users (e.g. users in femtocell networks) subject to the interference-limit constraint for primary users (e.g. users in cellular networks) and quality-of-service...
We consider a complex, additive, white Gaussian noise channel with flat fading. We study its diversity order vs transmission rate for some known power allocation schemes. The capacity region is divided into three regions. For one power allocation scheme, the diversity order is exponential throughout the capacity region. For selective channel inversion (SCI) scheme, the diversity order is exponential...
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